Coaxial connectors are manufactured in predetermined sizes and with predetermined nominal impedances, such as 50 ohms or 75 ohms. One type of miniature coaxial connector is the size 8, 75 Ohm D-sub connector whose center contacts include a pin of 0.04 inch (1 mm) diameter, and a plug outer shell of 0.153 inch outside diameter at the front portion and 0.188 inch outside diameter at the rear portion. Where a simple solid insulator is used that provides clearance only around a socket contact at the front portion, the front portion has an impedance of about 40 ohms and the rear portion has an impedance of about 85 ohms, resulting in an average of about 65 ohms, which is considerably less than the desired 75 ohms. The impedance can be raised by constructing the insulator with air spaces, but this can lead to a structurally weak insulator that is easily damaged during insertion of the center contact, especially because of the small size of the parts of the miniature connector. It should be noted that low cost dictates that the insulator be a one-piece molded part. A low cost miniature coaxial connector whose impedance was closer to the nominal impedance, such as 75 ohms, but which was still of rugged construction, would be of value.